My first solution

[juanmiuk <juanmiuk@googlemail.com>]

with Ada.Strings.Fixed;
use  Ada.Strings.Fixed;

procedure Test_2 is

     subtype My_Num is Integer range 1 .. 10;

     function Format_Num ( Width_Num  : Integer;
                                       The_Number : Integer ) return
String is

        Temp_Length : My_Num := My_Num'Image(The_Number)'Length;
        Separador      : String := (Width_Num - Temp_Length) * ' ';

        begin
             return (Separador & My_Num'Image(The_Number));
        end Format_Num;

begin
     for I in My_Num range 1 .. 10 loop
        declare
            Output : String := Format_Num(My_Num'Width, I);
        begin
            Text_IO.Put_Line(Output);
        end;
    end loop;
end Test_2;